There is no way to set the compression ratio.  Think of it like trying
to determine the amount of compression that pkzip in windows or compress
in Unix will have of any given file. 

Its highly dependent on the type of data and no way to predict since you
data will always be variable, unless you have nothing but a single file
full of the same letter, then I'm sure there is some funky ten page math
calculation that you could use (and since I only have 10 fingers to
count on that leaves me out).

So In general In usually count on 130 - 140 percent compression.  The
last exception that I can recall was when I was at a client that was
backing up a large number of JPG images, which by nature are in a
compressed format, so I was getting 0 percent compression most of the
time. 

Sean


-----Original Message-----
From: veritas-bu-admin AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu] On Behalf Of Sen
Sent: Monday, May 05, 2003 6:50 AM
To: Matt Moody
Cc: netbackup-l; nbu-lserv; veritas-bu AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] number of tapes

how do i set the Compression ratio ??

----- Original Message ----- 
From: "Matt Moody" <mattm AT m-c-s DOT com>
To: "Sen" <discussion.groups AT gmx DOT net>
Sent: Sunday, May 04, 2003 3:35 PM
Subject: RE: [Veritas-bu] number of tapes


> DLT8k drive assuming non-compressed will require 4 tapes for the
backup.
> Compressed 2:1 will require 2 tapes.
>
> ASCII data (text) is highly compressable whereas .pdf's and some image
types
> are not very compressable.  Assume 3 tapes, expect less required.
>
> Matthew Moody
> MCSI
>
> -----Original Message-----
> From: veritas-bu-admin AT mailman.eng.auburn DOT edu
> [mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu]On Behalf Of Sen
> Sent: Sunday, May 04, 2003 1:07 AM
> To: Matt Moody; netbackup-l; nbu-lserv;
> veritas-bu AT mailman.eng.auburn DOT edu
> Subject: Re: [Veritas-bu] number of tapes
>
>
> i am using DLT 40/80
> how do i know the estimated data compression?
> its a 1 time backup, keep for 1 month
>
> ----- Original Message -----
> From: "Matt Moody" <mattm AT m-c-s DOT com>
> To: "Sen" <discussion.groups AT gmx DOT net>; "netbackup-l"
> <netbackup-l AT yahoogroups DOT com>; "nbu-lserv"
<nbu-lserv AT dsihost-srv01 DOT com>;
> <veritas-bu AT mailman.eng.auburn DOT edu>
> Sent: Sunday, May 04, 2003 2:00 PM
> Subject: RE: [Veritas-bu] number of tapes
>
>
> > What tape drives will you be using?  How much estimated data
compression?
> > Are you talking a one-time backup or a backup rotation.  If
rotation,
how
> > long will you be keeping the data?
> >
> > Matthew Moody
> > MCSI
> >
> >
> >
> > -----Original Message-----
> > From: veritas-bu-admin AT mailman.eng.auburn DOT edu
> > [mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu]On Behalf Of Sen
> > Sent: Saturday, May 03, 2003 11:34 PM
> > To: netbackup-l; nbu-lserv; veritas-bu AT mailman.eng.auburn DOT edu
> > Subject: [Veritas-bu] number of tapes
> >
> >
> > Hi,
> > how many backup tapes do you think is required for 150GB of data?
> >
> > Thanks
> >
> > _______________________________________________
> > Veritas-bu maillist  -  Veritas-bu AT mailman.eng.auburn DOT edu
> > http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu
> >
> >
> >
>
>
> _______________________________________________
> Veritas-bu maillist  -  Veritas-bu AT mailman.eng.auburn DOT edu
> http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu
>
>
>


_______________________________________________
Veritas-bu maillist  -  Veritas-bu AT mailman.eng.auburn DOT edu
http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu